The calculated distance (air line) between Naas and Dún Laoghaire is approximately 23 miles respectively 36 kilometers.
By car or train, the actual journey to Dún Laoghaire is certainly longer, as only the direct route (as the crow flies) between Naas and Dún Laoghaire has been calculated here.
Air line (approximately)
36 kilometers
20 nautical miles